2. Use the concept of average kinetic energy to explain why the temperature of a liquid remains constant while it is being boiled, although heat continues to be absorbed. Describe (explain) what happens to the heat that is absorbed. 3. The following graph shows the plot of temperature versus time as heat is added to a pure substance. Temp. 0 4 Time minutes a. During what period of time was the substance at its normal freezing point? (1 point) b. Over what period of time was the substance boiling? (1 point) c. What is happening to the substance between the 1 and 1.5 minute marks? d. What is happening to the substance between the 2 and 3 minute marks? e. What is happening to the substance between the 3.5 and 4.5 minute marks? f. What is happening to the substance between the 5 and 7 minute marks? 4. At -92C, a pure sample of HBr has a higher vapor pressure than a pure sample of KBr. Create visual representations that show the interactions between the particles in both samples during vaporization. a. b. Explain why the vapor pressure of HBr is higher than the vapor pressure of KBr at -92C